Heat exchanger



July 20, 1965 F. DRUsElKxs ETAL 3,195,626

HEAT EXCHANGER 3 Sheets-Sheet 1 Filed July 9, 1962 M 0 om; WEEE S/ E wwww@ .6 MT RRR ff DBI. 60M mi.

ATTU/PA/Ey July 20, 1955 F. DRusElKls ETAL. 3,195,626

HEAT EXCHANGER (E n INVENTORJ N FREDE/P/CK DRl/sE/K/s E IMBERT W ALTTOFNEV July 20, 1965 F. nRusElKls ETAL, 3,195,626

HEAT EXCHANGER 3 Sheets-Sheet Z5 Filed July 9, 1962 INVENTORS FEEDER/cfrRusE//f/s R spr m HALEY PA aL fa A60/vaak@ A TTORNEV United StatesPatent O eration of Delaware p Filed .luly 9, 1962, Ser. No. 203,316

7 Claims. (Cl. 16S-179) This invention pertains to heat exchangers, andparticularly to a heat exchanger having internal and external extendedsurfaces.

Heretofore, sheet metal heat exchangers having internal and externalextended surface portions, in the form of tins, have been made fromstrip stock having laterally otlset edges, which strip stock is spirallywound with adiacent convolutions overlapping and rigidly united. to forma tube. This type of heat exchanger tube has spiral internal andexternal tins which lfacilitate the exchange of heat between fluidsinside and outside thereof. The pres-V ent invention relates to a heatexchanger comprising a plurality of rings arranged in stacked relation,each ring having an external annular iin and a plurality of spiral, orhelical internal iin segments. When the rings are assembled in stackedrelation and rigidly secured together, they form a tube having spaced,external annular ns and internal spiral fins which deiine a plurality ofhelical passages therethrough.

Accordingly, among our objects are the provision of an improved extendedsurface tubular heat exchanger; the further provision of a tubular heatexchanger having equidistantly spaced, parallel, external annular tinsand segmental helical internal fins which define a plurality of helicalinternal passages therebetween with a central opening therethrough; thefurther provision of a heat exchanger of the aforesaid type having coremeans for the central opening defined by the inner edges of thesegmental internal helical fins; and the still further provision of animproved heat exchanger section, or ring, having an annular externaltin, an annular body with multiple otlset portions, and a plurality or"internal helical n segments.

The aforementioned and other objects are accomplished in the presentinvention by nesting, or intertting, the annular body portions of aplurality of heat exchanger sections to orm a tubular stack with theradial ends of the internal helical segmental fin portions or" adjacentsections abutting, and thereafter rigidly securing the plurality ofsections together by copper brazing or Welding. Specilically, asdisclosed, the annular body of each heat exchanger section is formedwith multiple oitset portions between its ends to provide spaced,intermediate annular stop shoulders. One edge of each section isoutwardly flanged at right angles to the annular body to form an annularexternal lin, and the other edge is formed with four inwardly extendinghelical iin segments, the inner peripheral edges of which denne acircular central hole. The internal helical lin segments of the stackedheat exchanger sections define four spiral passages therethrough. Thetubular heat exchanger can be used with or without a central core which,if used, completely closes the central hole through the stackedsections.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein preferred embodiments of the present invention areclearly shown, and wherein similar numerals depict similar partsthroughout the several views.

and partly in elevation, ot a forced warm air furnace ldh Patented.lilly 2t), i955 embodying the heat exchanger of the present invention,taken generally along line l-ll of FIGURE 2.

FIGURE 2 is a fragmentary view, partly in section and partly inelevation, with certain parts broken away, taken along line 2-2 ofFIGURE 1. s

FIGURE 3 is an enlarged fragmentary sectional view taken along line 3 3of FIGURE 1.

FIGURE 4 is an enlarged perspective view of one end of thc improved heatexchanger section.

FIGURE 5 is an enlarged perspective view o' the other end of theimproved heat exchanger section.

FIGURE 6 is a fragmentary View, partly in section and partly inelevation, or" a modified form of the heat exchanger.

With reference to FGURES l and 2, the improved heat exchanger is shownin combination with a forced warm air furnace having a casing Il@comprising front, rear and side walls, with a top wall l?. suitablysecured thereto and a bottom wall, not shown. In addition, the casinglil has an intermediate substantially horizontal partition wall i4:dividing the casing into an upper compartment lo and a lower compartmentt8. A conventional motor driven blower 2t? is located in the lowercompartment ld, the blower, when operating, discharging air to be heatedinto the upper compartment le for delivery through an opening 22 in thetop Wall l2. The upper chamber ld has a vertical partition 2d attachedto the top wall 12 and the horizontal partition lid, the partition 2dconstituting a mounting plate for a lue gas collector box 26 and anintegral combustion shell and heat exchanger assembly 2S, the collectorbox 2d and the assembly 2S being disposed on opposite sides of thepartition panel 24. The interior or the tlue gas collector boxcommunicates with a stack 3d through an opening in the top wall l2 ofthe casing.

The integral heat exchanger and combustion shell assembly 23 is shroudedby a pair of side battles 31 which coniine air flow from the blower to apath contiguous to the extended surface portions of the heat exchanger.The assembly 2S comprises a header 32 which is supported by a bracket354, and has a plurality of substantially vertically extending,laterally spaced U-shaped tins 36 welded, or brazed, to its end wall.The integral cornbustion shell and heat exchanger assembly 23 alsocomprises a multiple section, externally inned combustion shell 3d, anda pair of multiple section, externally iinned heat exchanger tubes (lil.A fuel burner ft2 is supported by the partition panel 2d and extendsinto the tubular combustion shell 3b.

Referring to FIGURE 3, the combustion shell 38 comprises a plurality ofnested, or interlitting, rings dil. Each ring di has an annular bodywith an outwardly extending annular iiange 4d along one edge and aninwardly extending annular lange ed at its other edge, with an otlset inits annular body intermediate its edges to forni an annular stopshoulder Thestop shoulders Sti on the rings 44 enable the plurality ofrings dil to be assembled in stacked, nested relation to form a doublethickness wall, which nested, or intertted, rings are rigidly securedtogether such as by welding, or brazing. The inwardly extending annularllanges define a central circular opening 52 for accommodating theburner ft2. A cornbustion shell mounting ring 54 has a neck portion 56suitably secured to the periphery of an opening in the partition panel24, and supports a transfer ring 53. Both the mounting ring 54 and thetransfer ring 5S have outwardly extending annular ianges do, the llangeslo on the several sections constituting integral extended surfaceportions, or tins.

The header 32, as seen in FIGURE 3, comprises a junction plate at) and adishshaped cover 62, the cover 62 having a flanged edge d4 over whichthe edge 66 of the aisance tion 63 adapted to interfit with the end ring44 of the combustion shell.

Thus, the ring portion 68 is offset intermediate its edges to form anannular stop shoulder 7 y for the end ring 44, and likewise has aninwardly extending annular flange portion 72 at its outer edge. It is tobe understood that the end ring 44 is welded or otherwise suitablyconnected to the ring portion 68.

. Referring to FIGURES 4 and 5, each heat exchanger tube 4% comprises aplurality of nested, or interfitted, ring, or cup, sections 74. Therings 74 are preferably formed of sheet metal which is stamped and drawnto the desired form. Each ring 74 has an annular body 76 with a pair ofodsets between its ends to provide axially spaced annular shoulders 78and 80 of different diameter. In

' the assembly of the rings only one of the shoulders 78 or @il is usedas a stop. One end of each ring 74 is formed with an outwardly extendingannular flange 82, and the other end of each ring is formed with fourinwardly extending segmental helical fins S4. Each segmental helical nS4 has axially offset, substantially radial ends S6 and 8S, with theends adjacent the fins being in substantial alignment with each otheralthough axially spacedN apart. The inner peripheral edges Siti of thesegmental fin 84 are arcuatey such that when a plurality of rings '74are interfittedwith each other, ,the radial ends of the helical finsegments of adjacent rings abut each other, and the inner peripheralarcuate edges 90 define a substantially circular hole 92 throughfthetubular heat'exchanger 4t) as seen in FIGURES l and 3.

Each heat exchanger tube 40 comprises a stack of interfitted rings 74,each shoulder Sti forming a seat, or stop, for each adjacent ring so asto equidistantly space the annular external flanges, or fins, 82 whichlie in spaced parallel planes. The offset portions of the annular bodies76 of adjacent rings form a continuous double thick-V ness side wall foreach heat exchanger tube 40, adjacent rings being rigidly securedtogether such as bywelding, or brazing, the offset annular body portionsthereof. In addition, during assembly of the rings 74 to form the heatexchanger tube 40, the axially outward offset radial ends 83 of the foursegmental helical fins l84 of each ring 74 are arranged to abut theaxially inward offset radial ends 86 of the segmental helical fins ofthe'next succeeding ring 74 from theheader 32 to the partition panel 24.By so interfitting the rings 74 four separate and distinct spiral, orhelical, passages 94, 95, 96 and 97 are formed by the segmental internalhelical fins of the several rings 74 throughout the length of each heatexchanger tube 4t). Each helical passage 94, 95, 96 and 97 makes acomplete turn through the axial distance of four rings 74. Moreover, asalluded to hereinbefore, the interfitted rings 74 define a substantiallycircular central through passage 92.

.The junction plate 60 is formed with a pair of integral ring portions9g adapted to interfit with the end ring 74 of each tubular heatexchangerV 40.V Each ring portion Sie has two intermediate offsetsforming an annular stop shoulder lili), the end ring 74 being welded orotherwise suitably connected to the ring portion'98.

At the other end of each heat exchanger tube, the shoulder 3i) o endring 74 seats against a complementary oset portion of a mounting ring1tl6 having a shoulder we. The mounting ring 106 has its inner edge 110clinched over the peripheral edge 114 defining an opening in thepartition panel 24.V A transfer ring 116 seats against the shoulder 103of the mounting ring 106, both the transfer ring 116 and the mountingring 106 having outwardly extending annular tins 82.

In a modified embodiment as Ashown in FIGURE 6, the heat exchanger tube4@ has a central tapered core 126 with an imperforate end cap 122, thecore 126 extending through the circular opening 92 formed through thenested vring sections 74 so aslto 'substantially close the same.

In this embodiment the flow of fluid internallyV of the heat exchangertube 40 is substantially confined to the four helical passages 94, 95,96 and 97 formed by the internal'segmental helical fins of the ringsections 74. While the Vcore 12@ increases the restriction to flowthrough the heat exchanger tube, it also increases the efficiency ofheat transfer between the internal and external fluids, be they gaseousor liquids, since substantially all of the internal fluid must flow inmultiple spiral paths and is thus in intimate contact with the internalcxtended surface portion-s of the heat exchanger tube throughout itslength. The core can be of different lengths, as shown in phantom inFIGURE 6, to obtain the desired heat transfer eiciency.

In both embodiments of the improved tubular heat exchangers disclosedherein, thegnumber of internal helical passages formed'by the segmentalhelical fins can be changed by varying the number of regimental helicalVfins on each ring section. The extent of the axial flow required for acomplete turn, or revolution of the fluid through the helicalpassages isdirectly proportional to'the number of segmental helical fins on eachsection. Thus, with the specifically disclosed ring sections, the fluidtraverses an axial distance of four'ring sections while making acomplete turn.' The multiple helical passages greatly increase theefiiciency of heat transfer between the internal and external tiuids.

While the embodiments of the invention as herein disclosed constitutepreferred forms, it is to be understood that other forms might beadopted.

We claim: l

1. A tubular heat exchanger including,- a plurality of interiittingrings, each Vring comprising an annular body having an outwardlyextending, annular fin at one end and a' plurality of inwardlyextending, segmental helical fins at Vits other end, stop means on saidannular body engageable with the adjacent ring Vto space the annularfins equidistantly apart, the ends of the segmental helical fins ofadjacent rings abutting each other and defining a plurality of internalhelical passages in the heat exchanger equal to the number of `segmentalhelical tins on each ring.

2. A tubular heat exchanger including, a plurality of interfitting"rings, each ring comprising an annular body having an external, annularfin at one end and a plurality of internaL'segmental helical fins at itsother end, means on said annular body defining a stop for the adjacentring to space the external fins equidistantly apart, the internalsegmentalv helical fins of each ring having arcuate inner peripheraledges with the internal segmental helical tins of adjacent ringsabutting each other to define a plurality of internal helical passagesin said heat exchanger equal to the number of internal segmental helicalfins on each ring, the arcuate inner peripheral edges of the internalsegmental fins on adjacent rings defining a substantially cylindricalpassage through the heat exchanger.

3. The tubular heat exchanger set forth in claim 2 including a tubularcore having a closed outer end disposed Within said substantiallycylindrical through passage so as to substantially close the centralthrough passage.

4. A tubular heat exchanger including, a plurality of interfittingrings, each ring comprising an annular body having an external,annular'fin at one end and a plurality of internal, segmental helicalfins at its other end, means on said annular body constituting a stopfor the adjacent ring tospace the external fins equidistantly apart,adja- Y cent internal segmental helical fins of each ring having axiallyoffset, radially aligned ends, the axially outward offset ends of thesegmental helical fins on each ring abutting the axially inward offsetends of the segmental helical fins on the next adjacent ring to define aplurality of internal `helical passages Vin the heat exchanger equal tothe number of segmental helical fins on each ring.

5. A tubular he'at exchanger including, a plurality of interfittingrings, each ring comprising Van annular body having an external, annularfin at one endand a plurality of internal, segmental helical fins .atits other end,

area-5.26

means on said annular body constituting a stop for the adjacent ring tospace the external fins equidistantly apart, adjacent internal segmentalhelical tins on each ring having axially offset aligned, substantiallyradial ends, the radial ends of the segmental helical ns of adjacentrings abutting each other and defining a plurality of internal helicalpassages in the heat exchanger equal to the number of segmental helicalns on each ring with each helical passage making a complete turnthroughout the axial distance of the number of intertting rings equal tothe number of internal segmental helical tins on each ring.

6. The tubular heat exchanger set forth in claim 5 wherein the means onthe annular body constituting a stop for the adjacent ring comprises anolset in said an- 15 nular body intermediate its ends delining anannular stop shoulder.

7. The tubular heat exchanger set forth in claim 5 wherein the innerperipheral edge of each segmental helical tin on each ring is arcuate,and wherein adjacent arcuate inner peripheral edges of the internalsegmental helical tins of said plurality of interfitting rings define asubstantially cylindrical passage therethrough.

References Cited by the Examiner UNITED STATES PATENTS 1,886,533 l0/32Thomas 165-179 2,703,701 3/55 Simpelaar 165-141 2,925,830 2/ 60Kantrowitz 165-179 3,068,905 12/ 62 Millington et al 165-179 X FOREIGNPATENTS 514,015 ll/20 France.

CHARLES SUKALO, Primary Examiner.

1. A TUBULAR HEAT EXCHANGER INCLUDING, A PLURALITY OF INTERFITTINGRINGS, EACH RING COMPRISING AN ANNULAR BODY HAVING AN OUTWARDLYEXTENDING, ANNULAR FIN AT ONE END AND A PLURALITY OF INWARDLY EXTENDING,SEGMENTAL HELICAL FINS AT ITS OTHER END, STOP MEANS ON SAID ANNULAR BODYENGAGEABLE WITH THE ADJACENT RING TO SPACE THE ANNULAR FINSEQUIDISTANTLY APART, THE ENDS OF THE SEGMENTAL HELICAL FINS OF ADJACENTRINGS ABUTTING EACH OTHER AND DEFINING A PLURALITY OF INTERNAL HELICALPASSAGES IN THE HEAT EXCHANGER EQUAL TO THE NUMBER OF SEGMENTAL HELICALFINS ON EACH RING.